Dual-functional active frequency selective surface using parallel feeding configuration and its equivalent circuit model

Abstract

A dual-functional active frequency selective surface (AFSS), which integrates two independent and dividable functions, is presented in this article. The proposed structure consists of two orthogonally arranged metallic layers, separated by a thin dielectric layer. Different active devices, including varactor diodes and PIN diodes, are loaded on top and bottom metallic layers, separately. Thus, the frequency tuning function for transverse magnetic waves and the electromagnetic switching function for transverse electric waves can be attained, respectively, by controlling the working states of these active components. In addition, a novel feeding configuration is designed to mitigate the negative impact of the bias network and provide parallel feeding topology simultaneously. Detailed equivalent circuit models for different polarizations and states are constructed to characterize the AFSS structure. Finally, a prototype of the proposed structure is fabricated and measured for verification, and the experimental observations agree well with the simulated results. This dual-functional AFSS could be an important step toward multifunctional AFSSs that are endowed with more than two electromagnetic functions.